Fill in the stepped gradations with foam putty. Run out of foam putty after three jars, and order a case of it shipped overnight. (That hole in the background is the reservoir.)
Step five-b:
Allow putty layers to dry. Allow putty layers to dry some more. Run a
hairdryer over the putty. Give up on putty. Go home and make trees, while
your partner tests copper finishes on polystyrene siding material. (The
holes are the water retention basins.)
Come back the next day and find that the putty is still NOT dry. Have fun making the little steps and the sculptural wall by the old sales gallery entrance. Go home and make more trees.
The putty is mostly dry. Sand the putty. Sand the putty some more. Sand the putty again. Run out and buy more sandpaper.
Curse the *%@!! putty as you sand it-it goes faster that way. Shake the putty dust out of your hair. Vacuum up the piles of putty dust off the carpet, the walls, the model, yourself and the cat.
Lay carbon paper over entire base, and trace lines from the taped-together master site plan onto the base to see what REALLY needs sanding and what doesn't. Drink wine. Go home and make more trees, while your partner prints out teeny windows and doors on acetate from CAD files.